HYDRA FPB-77: Biocide Treatment for Petrol, Kerosene & Diesel

Our Price:  £13.15(Inc. 20% VAT)(£10.96 Exc. VAT)
Pack Size:

  (24 Reviews)
  • 500ml Treats up to 5,000 litres of all liquid fuels
  • 5 Litre bottle comes with free dosing bottle
  • Quickly removes harmful bugs (microbes) including diesel bug in all fuels.
  • Highly effective in all liquid fuels and their water phase.
  • Stops excess sludge build-up, keeps fuel stable for over 2 years.
  • Stops blocked lines and filters, ensures long-lasting protection.

Brand:  HYDRA





  • Stored/remaining fuel in the fuel tanks remain protected against microbes for long periods.
  • Immediately rids all contamination and prevents the regeneration of microbes including bacteria, fungi, yeast and mould.
  • Hydra FPB-77 FuelPlus is soluble in both fuel and water phases for better and efficient killing.
  • No more fuel lines or filters that are blocked. Prevents clogging of injectors. Prevents failures of the fuel system.
  • Cut’s down expensive maintenance cost of bunker fuel and improves fuel economy.
  • Safe to use as non–flammable, non-toxic, non-corrosive. Totally combustible in the fuel mixture and compatible with all engine materials.
  • Maintenance dose rate 100ppm.


Shock / Initial Dose: 1: 3,000 (30 ml per 100 litre fuel)

For microbe contaminated fuel system.

Add to the existing fuel tanks at the recommended dosage to remove all damaging microbial growth.

Refuelling Dose: 1:10,000 (10 ml per 100 litre)

To protect the clean fuel system Add the recommended re-fuelling dose in the tank before topping up with a fresh supply. Ensure the addition of treatment refuelling dose every time the tank is topped up.

Add to fuel tank then top up with new fuel. Fuel tanks being treated should be at least 10% full. 


All fuel tanks, including bulk fuel storage tanks that are used for storing Diesel, Gas Oil, Ultra Low Sulphur Diesel (ULSD) and Residual Fuels will contain some water.

The stored fuel also absorbs moisture from the atmosphere, this water leads to microbial contamination and microbial fuel bug problem, for diesel it is commonly called the diesel bug.

Fuel tanks can accumulate as much as 0.1% water (based on the type and volume of fuel) as a result of condensation during long-term storage.

As freshly refined fuel cools down, its water solubility decreases. Henceforth, moisture, which was previously dissolved in the fuel begins to drop out of the fuel. This process continues throughout the fuel’s cooling process even during transport.  As fuel’s specific gravity is lower than that of water, as dissolved water condenses it tends to drop out of fuel, accumulating in tank bottoms and in pipeline low-points.

As waters specific gravity is greater than that of fuels, as dissolved water condenses, it tends to drop out of the fuel product, accumulating in tank bottoms and in pipeline low-points.

Fuel can be stored for a long time before the sale and this fuel will contain a certain amount of water.

Biological Diesel (FAME) especially has a tendency to hold more water compared to conventional diesel fuel.


Fuels left for storage in fuel tanks will always contain some water. The amount of water present will gradually increase with time. The longer the fuel is left undisturbed the more water it will contain.

Fuels are usually stored for a considerably long time before it reaches the customer therefore will always contain some water. Biological diesel such as (FAME), tends to hold more water than conventional diesel. The accumulated water is an ideal environment for the microbes to thrive and contaminate the fuel severely compromising the consistency and quality of the fuel.


When you clean a fuel tank and need a clean fuel system, it is essential to use the correct product when cleaning fuel. Hydra FPB-77 FuelPlus has been used for years and is highly effective and keeps working. How to tell if your fuel is microbe contaminated, the fuel is usually darker than usual, with a dark slime build-up on the fuel filter.

Rapidly removes problem bio sludge build-up in fuel lines, fuel tanks, filters and injectors, as well as cleaning fuel systems will continue to protect fuel for up to 2 years. Used in cars, vans, trucks, boats, standby generators, heavy plant, farm equipment such as combined harvesters which are only used for a couple of weeks per year, classic cars, classic bikes which are only used in the summer months.


Effective in any hydrocarbon or bio-fuel product, effective in fuel and water phase as recommended by major engine manufacturers.

Thus, the bulk suppliers and operators both face technical challenges, since all fuels especially low Sulphur can exhibit specific issues which cause problems in operation. 

In hot countries and during long term storage this can especially be the case.

During long term storage, the quality of fuel can be severely affected due to the growth of harmful microbes, moulds, fungi and bacteria.

This microbial attack leads to fuel degradation, reducing fuel lubricity as fuel additives are broken down by the harmful microbes.

Spring and summer are the smartest times to examine your fuel system as the hot days and cold nights cause a lot of condensation in the fuel tanks. 

Contaminated fuel can result in loss of power from partially blocked fuel lines or plugged fuel filters, smoke emissions and even breakdowns from complete blockage of the fuel line.


Hydra FPB-77 FuelPlus Fuel Clean is the essential cleaner for your fuel system. Common dirty fuel issues included replacing filters more often, cleaning or replacing fuel injectors, black smoke at the start, premature engine wear of rings and cylinder liners caused by microbe produced acidic by-products, this leads to higher oil and fuel consumption.


Prevents blocked fuel lines, filters and clogged injectors - helps prevent fuel system failures.

Prevents excessive sludge accumulation.

Prevents attack to metal components and fuel tank corrosion from organic acids created by microbial growth.

Reduces expensive maintenance of diesel fuel and improves fuel economy.


Ideal for use when polishing fuel, this is when fuel is recirculated through a series of filters which remove fuel bio sludge build-up. However, this will not remove the build-up inside the tank, fuel lines, pumps, filters, injectors etc, the answer is to use Hydra FPB-77 FuelPlus for a very thorough clean of all internal fuel system components, whilst fuel polishing and to protect fuel after cleaning.


These issues can be solved by Hydra FPB-77, which is an excellent fuel protection treatment. It has proven to be the economical solution for improving the quality of fuel and its properties.

Hydra FPB-77 removes harmful microbes in all liquid fuel, including marine. Removes microbes completely within 24 hours, keeps protecting the treated fuel for over 6 months.  

Hydra FPB-77 is based upon dual Isothiazolone chemistry and technology that has been proven to be highly effective against microbial growth for over 25 years. Isothiazolones are registered under the ECHA European Biocides Directive, REACH and by the EPA in the USA.

Hydra FPB-77 provides long-term protection by preventing algae and fungi re-growth, which can also damage the fabric of the fuel tanks. Totally eradicates microbial growth in fuel systems. 


Laboratory tests of Hydra FPB-77 have been taken against micro-organisms isolated from contaminated fuels i.e. Pseudomonades, sulphate-reducing bacteria and the main source of the problem, fungi of the genus Candida, Cephalosporium, Penicillium and in particular Cladosporium res.

These tests prove the effectiveness of Hydra FPB-77 at in-use levels of only 100 ppm.


When dosed appropriately, Hydra FPB-77 is extremely effective for both the decontamination of heavily fouled fuel systems and the prevention of future microbial spoilage.

Hydra FPB-77 preserves your valuable fuel systems to prevent machine malfunction, engine failures, microbial induced corrosion and impaired water removal from storage tanks.

By preventing microbial growth, Hydra FPB-77 protects the fuel performance properties as well as specifications such as colour, heat of combustion, pour point and cloud point.

Also prevents fuel starvation damage to injectors and engines.


All of our products are manufactured to the highest specifications at our UK plant, which is accredited to ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018

How To Use: FPB-77


Shock Dose

Add 1 ml of Hydra FPB-77 to 3 litres of fuel.

Aircraft Only - Add 1 ml to 10 litres of fuel.

Preventative Maintenance

Add 1 ml of Hydra FPB-77 to 10 litres of fuel on each refill.

Aircraft Only - Add 1ml for each 20 litres of fuel.


Before using Hydra FPB-77, it’s recommended that you drain all the water from the tank first. When the storage tank is about one third full Hydra FPB-77 should be added. The Hydra FPB-77 will mix evenly with the rest of the fuel in the tank as the tank is filled up. Hydra FPB-77 will start working immediately on any wet sludge or residual water present in the fuel. The amount of Hydra FPB-77 to be used depends on the volume of the storage tank.

To treat severe microbial and fungal contamination, where sludge is visible and technical malfunction are present such as filter blockage, Hydra FPB-77 shock dose should be added to the fuel for the treatment. After 24 hours of Hydra FPB-77 treatment, the residual water if any and dead bio-sludge again should be drained off if possible.

For extremely severe sludge formation, the fuel tank, fuel lines and filters need to be cleaned before using Hydra FPB-77. Otherwise, in some case it may initially be necessary to change fuel filters more frequently as Hydra FPB-77 clears the bio-sludge from the system.

General Recommendations

Whatever method of addition is employed appropriate precautions should always be taken. Avoid any dermal contact. Suitable protective clothing should be worn (including rubber gloves and safety goggles / face shield).

Do not exceed solubility level of Hydra FPB-77 (approximately 5000 ppm or 5 litres Hydra FPB-77/ 1000 ltr of fuel).

Fuel tanks being treated should be at least 10% full. Never add Hydra FPB-77 into an empty fuel tank.

Do not exceed recommended dose levels for Hydra FPB-77.

Road Vehicles

It is impractical to dose Hydra FPB-77 directly into vehicle fuel tanks.

Instead fuel already treated with Hydra FPB-77 should be used.

Marine Vessels

Wherever feasible fuel tanks should be cleaned. As with road vehicles, direct addition of Hydra FPB-77 may be impractical. The use of fuel treated with Hydra FPB-77 is therefore the preferred method of addition.

Storage Tanks

In order to optimise distribution of Hydra FPB-77 addition into a flowing fuel stream is preferred. Either sludge or continuous feed dosing can be used. It should be noted however that other methods of addition, such as dumping, will not affect the performance of Hydra FPB-77.

NB: Hydra FPB-77 is not surface active. It will therefore encourage rather than inhibit water separation.


The partitioning characteristics of Hydra FPB-77 result in a higher concentration of active ingredient in the water phase than in the fuel phase. The exact concentration is dependent on several factors. The fuel/water ratio, the initial dose, length of storage rate of turnover and conditions within the tank will all influence the way the active ingredients partition between fuel and water.

As with most biocides at certain concentrations Hydra FPB-77 can be toxic to aquatic species. Therefore water bottoms or effluents must be diluted and/or deactivated prior to discharge into public waters.


Hydra FPB-77 is biodegradable and is non-persistent in the environment. Dilution to below effect levels will ensure its degradation - the greater the dilution factor the more rapid is the degradation. For guidance on approved discharge procedures contact Hydra International or consult local authorities.

Deactivation of Water

The active ingredients of Hydra FPB-77 are readily degraded to non-toxic components by the addition of slightly acidic 10% solution of sodium metabisulphite (Na S2O5) or sodium bisulphite (Na HSO3) in the ratio of 4:1 deactivation solution: Hydra FuelPlus.

Deactivation Must Not Take Place in the Storage Tank

When Hydra FPB-77 is used at refinery level another simple deactivation procedure can be employed. Water bottoms containing Hydra FPB-77 should be passed into waste waters from the hydrodesulphurisation process. The high levels of hydrogen sulphide levels present result in rapid deactivation of Hydra FPB-77.


What is diesel bug?

Diesel bug is the common name for microbial contamination in diesel type fuels. This contamination is caused by microbial bacteria that enter the fuel tank and feed on the fuel, it has become much more common as modern fuels now contain larger percentages of bio diesel components.

Water caused by condensation will also attract the growth of micro-organisms within the water phase, these same organisms will use the fuel as a nutrient source creating gums and resins building up as a layer inside the tank and fuel lines.

How do you treat diesel bugs?

Ideally, use Hydra FPB-77 to completely clean the fuel system. For shock treatment of a contaminated system use at 1:3,000. Maintenance Dose for protection of a cleaned system use at 1:10.000. Have on hand some extra fuel filters as they will need changing more regularly as the diesel bugs are removed from the fuel.

Equipment such as generators and farm equipment which are not used regularly are prime candidates for microbial contamination. Also due to the variations in the quality of diesel supply worldwide, especially for boats, you should always use a diesel bug treatment when refuelling.

How do you get rid of diesel fuel fungus?

Diesel fuel fungus spores are airborne, they enter the fuel tank and breakdown the hydrocarbon and bio elements that fuels now contain.

Hydra FPB-77 is what is known as a dual-phased biocide, this means it is as equally effective in both the fuel and water phases of fuel. Thereby ensuring complete eradication of diesel bugs from your fuel system. Your fuel filters will remove the dead microbes.

What are the symptoms of bad diesel fuel?
  • - Engines not running at full power.
  • - Fuel filters readily blocked with bio-slime and needing to be changed more often.
  • - Fuel is much darker than normal.
  • - Particles and sludge in the fuel, this is often a sign of microbial and fungi contamination.
  • - Difficulty in starting and increased fuel consumption.
  • - Bad smell coming from the fuel tank, often smell of rotten eggs.
  • - Excessive smoke from exhaust especially at engine start-up.
  • - Fuel injectors failing and showing indications of corrosion caused by the diesel bug.
How long does it take biocide to work?

You should always allow a minimum of 24 hours at a shock dose dilution rate to ensure a total kill of the diesel bug. After treating at shock dose, when refuelling ensure that the fuel tank is treated at the maintenance dose, this ensures that any surfaces missed because they were not in fuel contact during the initial treatment are now treated and protected.

I have purchased a 250 ml HYDRA FPB-77 FUELPLUS.  It will be used in a small fuel tank on our 24ft yacht the tank we think holds about 6 gallons. How much should I use ?

The measuring chamber at the top of the bottle has numbers on each side these are ml to put the correct amount of additive into the fuel. First Treatment - for 100 litres of fuel in your tank would add 30ml i.e. 1x25ml and 1x5ml shot. After the first treatment you dose for the fuel you are adding to the tank i.e. you add 100 litres.

Hi, what other additive (antifreeze and/or injector cleaner) is compatible with this?

Hydra DPB-100 Diesel Power Blast – Injector Cleaner

Hydra PIC-24 Petrol Power Blast – Injector Cleaner

Hydra Winter Cold Flow – Diesel Antifreeze

 Hi, I guess this is acceptable to use in white diesel & doesn't upset the customs men when dipping fuel tanks ?

Ans. This will have no effect on Customs & Excise dipping tanks, they are looking for a red indicator dye, none of our fuel additives contain any dyes.

Average Rating (24 Reviews):  
Write a Review and share your opinions!

New Review
07 July 2020  | 

First class service,fast delivery,great product at a good price,will deal again,many thanks.

Was this helpful to you?  Yes  /  No

2 of 2 people found this review helpful.

Fuel additive
22 April 2020  | 

I have given 5 stars for this review because I found no fault with the service received from Hydra Fuel Additives, But I must say I am not qualified to comment on how good the additive is I have used it in good faith that all is ok. Thank you for your service.
God Bless.
Uel Erwin


This review has not been appraised.

Getting a good job don
27 February 2020  | 

Cleaning Diesel on a narrowboat stove


This review has not been appraised.

Great Product
04 December 2019  | 

Great product and hopefully offset the clogging effect of the biodiesel fuel we are obliged to use!!!! Loss of 1 star due to delivery charge. We are neither the Highlands or the Islands and should not have been subject to a delivery charge.

Was this helpful to you?  Yes  /  No

1 of 1 people found this review helpful.

Hydra FuelPlus
21 November 2019  | 

Seems to work well. Only just started using it but it does seem to have solved the problem


This review has not been appraised.

Good tech advice
12 October 2019  | 

Very helpful tech support, not used product yet - - hope it will perform well.


This review has not been appraised.

Hydra fuel plus
31 July 2019  | 

Excellent product many thanks


17 of 17 people found this review helpful.

Excellent Service
11 July 2019  | 

Many thanks for fulfilling my recent order. The service was excellent with an easy ordering process and very rapid delivery.
I have now added the 'Initial Dose' to the large fuel tank in my barge. So, hopefully if it 'does what it says on the tin' it should make a big difference in cleaning up my fuel.


17 of 17 people found this review helpful.

good service and price
09 July 2019  | 

appears to be the best deal for this product


24 of 24 people found this review helpful.

The best professional company with high standard business ethics I've ever dealt with
06 April 2019  | 

Just like the company it does what it says on the tin just try


9 of 9 people found this review helpful.

Read all 24 customer reviews...

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